This invention relates to an air inlet for a heating or air-conditioning system of a motor vehicle comprising a controllable ram air flap arranged in an inlet duct for outside air as well as comprising a circulating-air flap which is swivellably disposed in an intake housing of the air inlet for blocking the outside air supply.
From German Patent Document DE 42 28 866 A1, an air inlet for a heating or an air-conditioning system of a motor vehicle is known, in which a circulating-air flap for blocking the outside air supply to the interior of the motor vehicle is provided in the intake housing of the air inlet. The circu- lating-air flap represents a shell-shaped curved body whose wall is curved in a spherical-segment shape. The circulating-air flap is swivellably arranged in the intake housing between a position exposing the intake duct of the air inlet and a position blocking this intake duct.
In order to achieve a constant ram pressure of the fresh air in the fresh-air intake duct also at higher driving speeds of the motor vehicle, a ram air flap is additionally arranged in the case of many motor vehicles in the area of the air inlet, which ram air flap can be controlled as a function of the pressure of the fresh air flowing into the air inlet. Such an arrangement of an additional ram air flap in the air inlet is not described in German Patent Document 42 28 866 A1. For providing such an additional ram air flap, additional bearings must be provided in the housing. In order to achieve an effective control of the ram air flap, in addition, the intake duct of the air inlet between the air inlet opening and the circulating-air flap must be lengthened in comparison to intake housings without any additional ram air flap.
It is an object of the invention to provide an air inlet of the initially mentioned type which has a compact and simple construction despite the arrangement of an additional ram air flap.
This object is achieved according to preferred embodiments of the invention in that the ram air flap and the circulating-air flap are arranged coaxially with respect to one another and are integrated in a common bearing in the intake housing. As a result, despite the arrangement of an additional ram air flap, the air inlet has a compact construction and, in comparison to the known prior art, has a much shorter inlet duct for the intake of fresh air. Since a common bearing in the intake housing is provided for the ram air flap as well as for the circulating-air flap, a relatively simple construction of the air inlet is achieved. Because of the solution according to the invention, an additional bearing for the ram air flap will not be required. As a result of the fact that the ram air flap is integrated into the bearing of the circulating-air flap which exists anyhow, it becomes possible to install an additional ram air flap in a simple manner into already existing intake housings. Because of the solution according to the invention, the ram air flap requires only the space which must be available anyhow for the circulating-air flap.
In a development of the invention, the ram air flap as well as the circulating air flap are formed as shell-shaped curved bodies whose walls are symmetrical with respect to the bearing axis. In a further development, the ram air flap is arranged radially inside the circulating-air flap and the moving paths of the ram air flap and the circulating-air flap are at least partially radially superimposed. As a result, one flap can be radially moved inside the other flap, whereby the two flaps can be arranged in a closely adjoining manner.
In a further development of the invention, the ram air flap and the circulating-air flap are connected with one another in a motion-transmitting manner by means of a kinematic forced control. As a result, by means of a common control unit, on the one hand, an independent control of the ram air flap in the opened condition of the circulating-air flap is permitted and, on the other hand, the ram air flap and the circulating-air flap are, nevertheless, jointly movable when the fresh-air supply is blocked.
In a further development of the invention, in which case a lower stop edge in the area of the intake funnel is provided for the exterior flap of the two air flaps and two upper stop surfaces fixed to the housing are provided for the closed and the opened end position of the air flap, the two stop surfaces fixed to the housing are provided on two stop ribs which are symmetrically aligned with respect to a perpendicular radial plane which contains the bearing axis and are arranged at a distance from one another, and the lower stop edge is arranged at a distance from a horizontal radial plane containing the bearing axis, which distance is larger than the distance of a stop surface from the perpendicular radial plane. As a result, it becomes possible to arrange the bearing axis relative to the intake funnel and therefore also relative to the blower at a larger distance, whereby an increased overall height is obtained for the housing of the kinematic forced control unit.
In a further development of the invention, the two stop ribs are connected by means of a transverse web to form a U-shaped profile. This is a development which is appropriate for plastic and by means of which the two stop ribs which are spaced with respect to one another can be connected with one another to form a stable profile which is sealed off to the outside.
In a further development of the invention, the U-shaped profile is molded as a circular-arc-shaped curved recess into the housing wall of the intake housing. As a result, the profile with the two stop ribs is connected in one piece with the housing wall of the intake housing and can already be molded in during the manufacturing of the intake housing consisting of plastic.
In a further development of the invention, for the purpose of a reinforcement, the U-shaped profile is provided with at least one transverse reinforcement along its circular-arc-shaped course. As a result, the U-shaped profile is reinforced along the circumference of the intake housing and therefore contributes to the reinforcement of the whole intake housing.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.